Think about that and I'll post the actual answer a bit further down....

Apparently it's "D" 5500 ft.
According to the book's explanation:
"Because the surface dewpoint temperature is given, you are required to account for its affect (sic) when calculating the cloud base.
The dewpoint decreases by 0.5 deg C /1000 ft, so the DALR of 3 deg C/1000ft is modified to 2.5 deg C/1000ft.

Now this, to me, appears to be bollocks. As far as I know the dewpoint temperature of the air doesn't change, it is what it is. I can't find anything that cooberates this. DALR is 3 deg C, and SALR is 1.5 deg C, ELR is 2 deg C. So where did the 5 deg C dewpoint lapse rate come from, if there is such a thing.

I'm doing my met at the moment too and find this stuff hard! I agree with your workings, and can't see anything about dewpoint temperature changing in the red pooley's book, however a search of the omniscient wikipedia does suggest that it changes: http://en.wikipedia.org/wiki/Lapse_rate#Significance_in_meteorology see the second paragraph of the "Significance in Meteorology" section:

Quote:

The dew point also drops (as a result of decreasing air pressure) but much more slowly, typically about −2 °C per 1,000 m

Yes it was wrong, but not for the reason you say. Of the four possible answers the nearest answer to 4600 is 4000.

However, in the posts further down and in the confuser 4000 is wrong because I failed to take into account the dewpoint temperature change per 1000 feet._________________PPL(H) R22, R44, R66 (0.05 hours )
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